1. Field of the Invention
The present invention relates to a power seat frame assembly and more particularly to a power seat frame assembly having a screw rod and nut assembly which is pre-assembled as a unit.
2. Description of the Prior Art
Generally, a power seat for vehicles uses a screw rod and nut assembly for slidable movement of a seat in the front and rear direction and/or vertical movement of a Dart of the seat cushion. Such a screw rod and nut assembly includes a screw rod supported at its ends on an upper rail, a nut engaged with the screw rod and secured to a lower rail or a seat cushion, and a reduction gear box operably connected to the screw rod and an electric motor for allowing the screw rod to be rotated. When the motor is actuated and the screw rod is rotated, the nut is linearly moved along the screw rod so that a linear movement of the seat or a vertical movement of a Dart of the seat cushion is obtained.
Problems encountered with this screw rod and nut assembly are that after the gear box is secured to a bracket which is fixed on the rail the screw rod has to be engaged with the gear box and a proper position of the screw rod with respect to the gear box and the seat cushion must be adjusted. This makes the arrangement of the screw rod and nut assembly complicated and requires excessive working time.